You have your own gigabit port from DSLAM to OLT at head end, then your own Cablelink from OLT, own link from CP equipment the Cablelink connects to to....?
I'm on FTTP, and I know that the GPON 2.4G down and 1.2G up is shared between no more than 32 users. For FTTC, OR has a good incentive to keep the DSLAM uplink uncongested, since it charges its customers for interconnect bandwidth.
With DOCSIS3.0 I believe it's 1.2G down and 200M up, shared by an indeterminate number. I do know several people who have experienced extreme congestion on VM, like getting well under 10M download at peak times.
As for cablelink and further up, backhaul is backhaul: it could be under-provisioned or over-provisioned in VM's network or anyone else's network. But at least with an OR-based service I have the option of switching to another ISP who has better capacity.